Building control systems encompass a wide variety of systems that aid in the monitoring and control of various aspects of building operation. Building control systems include security systems, fire safety systems, lighting systems, and heating, ventilation, and air conditioning (“HVAC”) systems. In large commercial and industrial facilities, such systems have an extensive number of elements and are highly automated.
The elements of a building control system are widely dispersed throughout a facility. For example, an HVAC system includes temperature sensors and ventilation damper controls, as well as other elements, which are located in virtually every area of a facility. Similarly, a security system may have intrusion detection, motion sensors and alarm actuators dispersed throughout an entire building or campus. Likewise, fire safety systems include smoke alarms, pull stations and notification devices dispersed throughout the facility. To achieve efficient and effective building control system operation, there is a need to monitor the operation of, and often communicate with, the various dispersed elements of a building control system.
One of the more important aspects of a building control system that requires monitoring is alarm status. Most or all building control systems employ alarms to indicate non-standard operation, including indications of equipment malfunctions and/or unsafe conditions. Fire safety systems, for example, issue alarms when smoke, or extreme heat is detected, or when a manual fire alarm pull handle device (“pull station”) has been activated.
To monitor alarm status, and/or other building conditions, building control systems typically have one or more centralized control stations in which alarm status and other data from the system may be monitored. Such centralized control stations also allow control over various aspects of system operation. The control station typically includes a computer having a processing circuit, data storage, and a user interface. To allow for monitoring and control of the dispersed control system elements, building control systems often employ multi-level communication networks to communicate operational and/or alarm information between operating elements, such as sensors and actuators, and the centralized control station.
In the past, control stations provided building control data exclusively in text format, which typically required intimate system knowledge to interpret and understand. As building control systems become more complex, it has become increasingly advantageous to present building system data in a more intuitive manner. Thus, control stations of building control systems now generally employ graphical user interfaces that combine text information with representative graphics to illustrate the context of the system data being displayed.
An example of the use of representative graphics may be the use of a thermometer shaped graphic to represent a temperature reading, as opposed to a simple one line text value. Similarly, the alarm status for a floor of building may be represented on a graphical display of the building floor plan, as opposed to a simple text list of alarm locations.
One example of a building control system control station that employs a graphical user interface in the control station is the NCC Workstation, available from Siemens Building Technologies, Inc. of Buffalo Grove, Ill., which may be used with the model MXL or XLS fire safety systems, also available from Siemens Building Technologies, Inc. In this system, several control stations, connected via an Ethernet or another type of network, may be distributed throughout one or more building locations, each having the ability to monitor and control system operation. As a consequence, different people in different locations of the facility may monitor and control building operations.
While the use of multiple networked control stations provides a high level of convenience and efficiency, there has been a growing need to be able to monitor and/or control systems from offsite locations.
To address this need, the use of Internet access to a building control system has been proposed, as discussed in U.S. Pat. No. 6,157,943 to Meyer (hereinafter the “943 patent”). The '943 patent describes a relatively straightforward system that incorporates ASP technology available from Microsoft Corporation of Redmond, Wash. to generate web pages that incorporate building control system information. The system described in the '943 patent builds graphical web pages that include building system data, and then transmits the graphical web pages to a web client. The '943 patent appears to describe the intended use of the ASP technology.
There are, however, significant limitations to the type of system described in the '943 patent. In particular, when building control system information is transmitted in a graphical image context, it requires significant bandwidth and download time. As a consequence, receiving updates over the Internet can be time consuming and inefficient as compared to receiving updates on a control computer that is connected directly to the building system network. While ongoing data communication developments improve Internet download speeds, it nevertheless can take significant time to download pages full of graphics. Moreover, if several clients access the same web server, the large, graphics-intensive downloads may slow the response time of the server, thereby also increasing the delay in receiving graphical build system user interface screens.
There is a need, therefore, for a method of providing faster and more frequent updates in a remote building system monitoring device using the Internet. Preferably, such a system would retain the ability present data in graphical format.